1. Field of the Invention
The invention relates to an organic electro luminescent display and a method for fabricating the same and, more particularly, to an organic electro luminescent display having an auxiliary layer encapsulating junction region and a method for fabricating the same.
2. Description of the Related Art
Generally, an organic electro luminescent display is an emissive display capable of emitting light by electrically exciting a fluorescent or phosphorescent organic compound, and phosphorescent organic compound can be driven by a low voltage and has a thin form-factor, a wide viewing angle and a fast response speed, so that the electro luminescent display can solve problems that have been found in liquid crystal displays. Therefore, the electro luminescent display has attracted attention as a next-generation display.
Such an organic electro luminescent display has a structure that has an organic light emitting diode (OLED) including an organic layer having at least emission layer(EML), an anode, and a cathode, wherein the organic layer having a predetermined pattern is formed on a glass or other transparent insulating substrate, and the anode and cathode electrodes are formed on upper and lower portions of the organic layer for applying a driving voltage to the organic layer. The organic layer consists of organic compounds.
In the organic electro luminescent display having the above-mentioned basic structure, as an anode electrode and a cathode electrode voltages are applied to the electrodes, holes injected from the electrode that have been applied with the anode electrode voltage are transported to the emission layer (EML) through a hole transporting layer (HTL), and electrons are injected from the electrode that have been applied with the cathode electrode voltage are transported to the emission layer (EML) through an electron transporting layer (ETL). The electrons and holes are then recombined in the emission layer(EML) to create excitons, and the exitons are then changed from an exciting state to a ground state, thereby emitting an organic substance of the emission layer (EML) and embodying a required image.
In the above-mentioned organic electro luminescent display, when a polymer material is used for the organic layer, the organic layer is generally formed on a substrate by spin coating. However, when the organic layer is formed by the spin coating, the organic layer is also formed in regions other than the pixel portion. Thus, the organic layer of the encapsulating junction region needs to be removed to encapsulate an inner structure of the organic electro luminescent display.
In a prior art, a cleaning process using an organic solvent was performed to remove the organic layer of the encapsulating junction region, however, the process has a significantly low accuracy and the organic solvent often penetrates into the pixel portion, so that there is a high possibility of damaging the pixel portion.
To solve the above-mentioned problems, a method using a laser is disclosed to remove a foreign substance including organic emissive materials off a substrate. According to a Korean laid-open Patent Application No. 2000-0036020, a method for removing the foreign substance using the laser is disclosed. This method removes organic or inorganic foreign substances on the substrate by directly irradiating the ultraviolet laser on the surface of the substrate.
In the case of the substrate of the prior art, a metal wiring and a passivation layer are usually deposited on a glass substrate in the encapsulating junction region. However, the laser energy absorption rate of the passivation layer is small so that the organic layer is not easily removed by using a laser.